Semiautomatic telephone-exchange system



R. L'. STOKELY 4 SEMIAUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Nov. 4, 1921 .4 Sheets-Sheet 1 Mary/val R. L. STOKELY SEMIAUTOMATIC TELEPHONE EXCHANGE SYSTEM,

Filed Nov. 4, 1921 arqlha/ Ver 4 Sheets-Sheet 2 IULWWIIH" R. L. STOKELY SEMIAUTOMATIC TELEPHONE EXQ'IANGE SYSTEM I Filed Nov. 4, 1921 4 Sheets-Sheet 5 Mumfor:

F4) 1. S/ake/y Dec, 2, R.'. L. STOKELY SEMIAUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Nov. 4, 1921 4 Sheets-Sheet '4 [Pay L. Sioke/y it an YATES RAY L. STOKELY, OF FLORAL "PARK, NEW YORK, ASSIGNOR '10 WESTERN ELECTRIC COMPANY, INCORPORATED, 013

NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SEMIAUTOMA'IIC TELEPHONE-EXCHANGE SYSTEM.

Application filed November 4, 1921. Serial No. 512,723.

To all whom it may concern:

Be it known that I, RAY L. S'roKnLY, a citizen of the United States, residing at Floral Park, Long Island, in the county of Nassau, State of New York, have invented certain new and useful Improvements in Semiautomatio Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and particularly to automatic toll switching trunk circuits, that is, to circuit arrangements for enabling the toll operators to build up toll connections to antomatic subscribers lines.

The object. of this invention is to improve the general operating efficiency of circuits of this character and to reduce the number of necessary manual operations.

One of the features of this invention is a circuit arrangement wherein the toll operators dial, common to her position, is automatically connected to a toll cord when the cord is inserted in the jack of an idle toll switching trunk leading to a machine switching oflice and automatically disconnected therefrom when it has completed the setting of the last numerical switch thereat, to avoid the necessity of further attention on the part of the operator after dialling, to manually disconnect the dial.

Another feature of the invention related to the above feature is the provision of a circuit arrangement whereby although the toll cord is connected to the toll switching trunk and the dial is connected to the cord to transmit impulses directly to the switches at the automatic ofiice to set the same, the relatively heavy current, which flows over the trunk from the automatic office and is interrupted to step the switches, cannot flow into the electroresponsive devices which must be provided in the toll cord for supervisory purposes. The connection of these devices to the toll switching trunk is automatically brought about only as a result of the inclusion of, resistances in the trunk at the automatic office after all the numerical switches have been set and, due to the con nection of these devices to the trunk, a signal is given the toll operator. The character of this signal is determined by the condition of the called line; that is, a signal of one character is given if the connector finds the line idle and a signal of another character is given if the connector finds the line busy.

Another feature is the provision of a circuit arrangement wherein if any selector finds the desired trunk group busy a signaling device, associated with the dial, is automatically operated, whereby the operator is notified not to transmit any more digits, and to release the switches already set.

Still another feature and related to the last mentioned feature is the use of said signaling device also to indicate that the apparatus for connecting the dial to the toll cord has functioned properly. Preferably this signaling device is a lamp located in proximity to the dial which lights when the plug is inserted in the jack if the relay which connects the dial to the cord has functioned. This la-mp is extinguished when the operator rotates the dial for the first digit and subsequently flashes if one of the selectors finds the desired trunk group busy.

Still another feature is the provision of acircuit arrangement whereby when the toll cord is inserted in a toll switching trunk jack leading to an automatic oflice the dial is automatically connected to the cord, but when the plug is inserted in a jack leading to a manual oflice the dial is not connected to the cord, and the electroresponsive devices referred to are immediately connected to the trunk to respond to current thereover applied at the manual office in which the trunk terminates.

Other features of the invention will be pointed out in the detail description.

Referring to the drawings, Fig. 1 shows a toll cord circuit and the operators dialing equipment common to the cord circuits of this position; Fig. 2 shows a toll switching trunk circuit leading to an automatic office and an incoming selector thereat; Fig. 3 shows a toll transmission selector; Fig. t shows trunk circuit terminating in a jack at a manual operators position.

The invention will be most readily understood from a detailed description of the operations involved in building up a connection.

The toll operator having received the number of the desired substation from the recording operator, or in any other suitable manner, touches the tip of her plug 100 to a toll connector; and Fig. 5 shows a.

the sleeves of the jacks such as 200 to select an idle trunk leading to the machine switching office in which the desired line terminates, and inserts the plug in an idle jack. Relays 201 (Fig. and 101 (Fig. 1) there upon operate in a circuit from ground, relay 201, inner left normal contact of relay 202, ring of jack 200, ring of plug 100, lower normal contact of relay 102, upper wind ing of relay 101, left normal contact of re lay 103, inner left normal contact of relay 104 to battery. Relay 101 at its armature 10? transfers the tip conductor 105 to conductor 106 leading to the dial 108 and at its armature 109 clOSQS a circuitto light pilot lamp 130, this circuit including the outer right armature of relay 104. The illumination of this lamp informs the operator that the relay 101 has connected he; dial 108 to the cord taken for use. Relay 01 at its lower armature disconnects relays Q10, 111, 11.2 from the sleeve of the plug and closes a locking circuit for itself and an operating circuit for relay 203 (Fig. 2) as follows: battery, normal contact of polarized relay 113, conductor 114:, lower winding of relay 101, lower armature and alternate contact of said relay, conductor 115, sleeve of plug 100, sleeve of jack 200. inner alternate contact of relay 20, relay 203, to ground. Relay 203 operates relay 202. Relay 202 at its right armature closes a locking circuit for itself to battery at the normal contact of relay 204. The continuity contact 205 of relay 202 holds relay 201 operated from battery at the alternate left contact of relay 203. The attr ction of the left armatures of relay completes the following operat ing circuit for the impulse relay 206 of the incoming selector at the distant machine switching ofiice: battery, lower winding of relay 206, armature 207 and normal contact of relay 208, ring trunk conductor 209, inner left armature and alternate contact of relay 202, ring of the jack 200, ring of the plug 100, ring conductor of the cord, lower normal contact of relay 102,. conductors 116, 117, polarized relay 113, conductor 118, right winding of relay 119, impulse springs of the dial 108, conductor 120, outer left armature and normal contact of relay 10st, conductor 106, armature 107 and its alternate contact. conductor 105, tips of the plug and jack 200, outer left armatureand alternate contact of relay 202, tip trunk conductor 210, armature 211 and normal con tact of relay 208, conductor 212, upper winding of relay 206, to ground at a normal contact of switch 213 operated on the 11th rotary step of the incoming selector brush shaft. Polarized relay 113 does not respond to this flow of current. Relay 200 in operating energizes the usual slow relay 214, which at its lower armature connects the Vertical magnet 215 of the incoming selector to the back contact of the impulse relay 200 preparatory to receiving impulses from the dial 108 in the well known manner. Relay 119 in the circuit traced for the impulse relay 206 operates in series with the impulse relay and at its right armature operates relay 103 in a circuit including conductors 122, 123 and the armature 109 and alternate contact of relay 101. Relay 103 in attracting its outer right armature closes a shunt about the outer left normal contact of relay 104: so that when; relay 10% is operated the dial is moved off normal. the loop circuit including the impulse relay 200 is not opened.

The toll operator .now rotates the dial 103 to transmit the first digit of the wanted number and the dial in moving oli normal closes contact 121 which closes a locking circuit for the left winding of relay 1.19 and also operates relay 104. Belay 104: in attracting its inner right armature locks to grounded conductor 123. In attracting its outer right armature it extinguishes lamp 130.

The dial 108 in rotating to normal interrupts the circuit of the impulse rela 200 a number of times corresponding to the first digit of the desired number. The vertical magnet receives impulses from impulse relay 206 in the well known manner and raises the selector to the desired. level. The selector then automatically hunts for an idle trunk leading to a toll transmission selector (Fig. The operation of the incoming selector (Fig. 2) will not be described in detail, since it is of the standard type shown and described for example in Patent No. 1,377,225 issued May 10, 1921 to A. J. Seymour. if the incoming selector (Fig. 2). fails to find an idle trunlg it operates switch 213 on its eleventh rotary step which opens the loop circuit including relays 200 and 119. This results in the deenergimtion of relay 119, since the circuit through its left winding is at this time open thus releasing relay 103 which at its inner right armature connects an interrupter 150 in circuit with lamp 130 which flashes to indicate an alltrunlrs-busy condition. Thereupon, the operator does not turn the dial for the remaining digits. but withdraws the plug 1.00 from jack 200 and waits and sets up the connection later. Relay 200 in releasing deenergizes relay 214: which closes the ch cuit of the release magnet 216 of the incoming selector in the well known manner.

Assuming, however, that the incoming selector (Fig. 2) finds an idle trunk, relay 208 operates and extends the trunk conductors 209 and 210 through to the toll transmission selector (Fig. 3), whereupon the impulse relay 300 thereof operates over the following circuit: free pole of battery, right winding of relay 300, inner right armature and normal contact of relay 301, normal right contact of relay 302, lower left-hand winding of the repeating coil BC to the lower talking conductor, over the path traced to the dial, returning over the upper talking conductor through the upper left-hand winding of repeating coil RC, left normal contact of relay 302, outer right armature and normal contact of relay 301, left winding of relay 300, switch 305, operated on the eleventh rotary step of the selector, to ground. The impulse relay 300 of the toll transmission selector and the relay 119 are energized in this circuit, the latter maintaining the relay 103 energized to prevent the flashing of the all-trunks-busy lamp 110, and the former operating the usual slow relay 303 to interpose at its left armature a break in the circuit of the release magnet 304 and prepare the circuit of the vertical magnet 306. Relay 303 in attracting its inner right armature grounds the release wire 307 leading back to the incoming selector to hold up the relay 208 after the slow relay 214 releases in the well known manner. This ground also causes the seized toll transmission selector to test busy to other incoming selectors. The operator now turns the dial for the next digit and upon the restoration of the dial, relay 300 transmits impulses to the vertical magnet 306 to raise the toll selector to the desired level. The slow relay 308 in series with the vertical magnet 306 operates a relay 309, this circuit including off-normal contact 310 and the outer right armature and alternate contact of relay 303. Relay 309 in attracting its left armature, locks itself over a circuit including the armature and normal contact of magnet 315, and the innermost armature and the normal contact of slow relay 312. Relay 308 also operates a relay 313, this circuit including the outer right armature and front contact of relay 303. Relay 313 looks in a circuit including its armature 314 and the outer right armature of relay 303. When slow relay 308 releases upon the termination of the vertical impulses the rotary magnet 315 is operated over a circuit including the right armature of relay 309, normal contact of relay 308 and outer right armature and front contact of relay 303. The rotary magnet steps the brushes onto the first trunk, and at the end of its stroke opens the locking circuit of relay 309 which releases, opening the circuit of the rotary magnet in the well known manner. If the first trunk is busy, its test multiple 316 is grounded and relay 309 again operates over a circuit including the off normal switch 310, armature and normal contact of the rotary magnet, conductor 317, armature 318, outermost right armature and normal contact of relay 312, conductor 319 to the grounded test multiple 316. Relay 309 again closes the circuit of the rotary magnet and locks in the circuit previously traced. The rotary magnet steps the brushes to the next trunk.

This interaction between the relay 309 and magnet 315 continues until an ungrounded test multiple is reached, whereupon the relay 320 operates over a circuit including relay 309, switch 310, normal contact of magnet 315, conductor 317, relay 320, to

ground at the outer right armature and contact of relay 303. Relay 309 is marginal and does not operate in this circuit. Relay 320 extends the conductors 321 and 322 to the impulse relay 400 of the toll connector which immediately operates over the following circuit: free pole of battery, right winding of relay 400, conductor 401, armature 402, and normal contact of relay 406, normal contact of relay 420, lower talking conductors (Figs. 4 and 3), lower right winding of repeating coil RC, left armature and front contact of relay 313, left winding of relay 323, upper right winding of the repeating coil RC, upper talking conductors (Figs. 3 and 4), armature 403 and normal contact of relay 406, left winding of relay 400, to ground. Relay 313 is not released due to the seizure of the toll connector since the contact operated by armature 324 is a makebefore-break contact. Relay 313 is thus held over the following circuit: free pole of battery, relay 313, armature 314 and its front contact, armature 324 and its alternate contact, control lead 325, conductor 404, armature 405 and normal contact of relay 406, sleeve conductor 407, contact 316, conductor 319, outermost right armature and normal contact of relay 312, armature 318 and alternate contact of relay 320 to ground at the outer right armature of relay 303. /Vhen the loop circuit was closed including the left winding of relay 323, a circuit was simultaneously closed through the right winding of said relay at the lowermost armature and front contact of relay 320. These windings neutralize each other and consequently relay 323 remains inert. Relay 400 operates slow relay 408 over a circuit including the upper winding of said relay and the lowermost armature and back contact of relay 406. Relay 408 in attracting its uppermost armature locks itself to the grounded control wire 404 and at its lowermost armature connects the vertical magnet 409 to" the back contact of the impulse relay 400, and opens the circuit of release magnet 410.

The locking circuit for relay 408 includes its uppermost armature and alternate contact. normal contact and armature 405 of relay 406, sleeve conductor 407, sleeve terminal 316 and its associated wiper, conductor 319, outer armature and back contact of relay 312, armature 318 and front contact of relay 320 to ground over the front contact and outer right hand armature of relay 303.

The operator now turns the dial for the tens digit, and the relay 400 transmits impulses to the vertical magnet toe to raise the connector to the desired level. The usual slow relay all is in series wit-h the vertical magnet. The first impulse for the vertical magnet passes by way of contact 412 of the olf-normal switch 413, and the succeeding impulses pass by way of contact 41%, and the armature and front contact of slow relay 111. Upon the cessation of the vertical impulses, relay 411 releases, connecting the rotary magnet 415 to the back Contact of the impulse relay 100. The operator now turns the dial for the units digit to rotate the brushes into contact with the desired line. The slow relay 4.16 in series with the rotary magnet upon its operation energizes slow relay 417 from the ground on the sleeve wire e07. llelay 416 in attracting its left armature operates relay 4:19 which looks to the sleeve wire 40?. When relay 416 releases, its right armature con nects relay 420 over the right armatures of relay 417 to the multiple e21 which it the selected line is busy is grounded. Relay ll? locks to the ground on this test multiple. Belay 420 operates from this ground and reverses the direction of the current flow in the trunk leading back to the relay 323 in the toll transmission selector ig. 3), which causes the electrically polarized relay 323 to operate. Relay 323 at its armature 327 operates relay 302 from the ground at the lowermost armature of relay 320. Relay 302 reverses th direction of current flow in the trunk leading back to the toll cord circuit, and includes resistances 340, 3&1 in the trunk circur to reduce the strength of the current to a value which will not injure the impedance coil 127 in the toll. cord which is of low resistance as described, to prevent signaling current from passing through the cord to the toll line 128 and give erroneous signals to the distant operator. Due to the reversal in the direction of the current flow in the trunk the polarized relay 113 operates and opens the locking circuit of relay 101, whereupon relay 101 releases, disconnecting the tip contact of the plug from the dial and extending them to the cord circuit. Relays 110 and 112 now operate over acircuit including normal contact of relay 101 and relay 203 now connected to the sleeve by relay 201. Relay 110 operates relay 102 which extends the tip and ring to the bridge containing the impedance coil 127 and supervisory relay 126. The coil 127 is of low resistance and impedance to signaling currents to prevent any signaling currents from passing to the toll line and is of high impedance to voice currents to prevent shunting the same. Relay 111 is marginal and only operates when plug 100 is inserted into a toll line jack (not shown) having a low resistance sleeve to cut off the bridge containing relay 126 in accordance with well known practice.

The supervisory lamp 125 in the toll cord now flashes to indicate the busy condition of the desired line. This is brought about in the following manner: Relay (F 3) in attracting its innermost left armature connects battery through an interrupter 328 to the lower winding of relay 329, the circuit being as follows: battery, interrupter 328, innermost left armature and front contact of relay 3.23, lower winding of relay 32$), armature 330 and front contact of r lay 313 to ground at the left armature and front contact of relay 300. Relay 329 in intermittently attracting its armature 331 applies an intermittent ground to conductor 332 which interniittcntly shunts out the supervisory relay 120 in the toll cord causthe flashing of the lamp 1 The operator thus knows that the line busy and attends to other duties, leaving the connection set up. 11s soon as the line becomes idle the ground is removed from its test multiple, which releases relays $17 and 420. Relay 4-17 in releasing its outer right armature, grounds the test multiples. Relay 417 in retracting its left armature, operates relay 106 from the ground on the sleeve wire 40?. Relay 4.06 in attracting its armature i205 opens the circuitpreviously traced tor the relay 313 and also the original locking circuit for relay 408. Relay 403, however, being slow-to-release, remains operated until relay 313 restores, whereupon it is held operated over a new holding circuit extending from grounded battery, through the upper winding of relay 108, front contact and outer upper armature of relay 108, conductor e104, conductor armature and front contact of re- 04/3: lay 320, armature 31 i and back contact of relay 313, outer left hand armature and back contact of relay 301 to ground over the back contact and armature 331 of relay 329. lielay 313 in retracting its left-hand armature opens th loop circuit including the left winding of relay previously traced. he lay thereupon releases, the polarizing circuit through the right winding of this relay to ground at the lowermost armature of relay 320 being insufiicient to hold relay operated. Relay 323 in retracting its innernmst left armature disconnects the interrupter from relay 329 and this relay remaining inert causes relay 126 in the toll cord to remain operated to maintain lamp 125 lighted. This serves as a ringing signal to the toll operator, who thereupon depresses her ringing key BK to impress ringing current on the trunk to operate relay over the trunk conductors in series. Relay 333 in attracting its armature operates relay 329 over a. circuit including the innermost left armature and normal contact of relay 323, lower winding of relay 329, armature 330 and normal contact of relay 313, and armature 334 and normal contact of relay lelay 329 in attracting its armature 331 opens the locking circuit previously traced tor the relay 408 (Fig. 4) which releases and applies ringing current to the selected line. Upon the response of the called party, relay 408 operates in the well known manner and again locks up to the grounded control lead 404 and completes the talking circuit. Relay 337 now operates in series with the called line over the following circuit: tree pole of battery, left winding of impedancecoil 336, relay 337, left-hand armature and back contact of relay 313, lower right-hand winding of the repeating coil, lower talking conductor, called line returning over the upper talking conductor, upper right-hand winding of the repeating coil, inner right armature of relay 313 to ground at the right winding of impedance coil 336. Relay 337 operates relay 301 which. in attracting its right armatures removes battery and ground from the trunk conductors leading back to the toll cord, and the outer right armature closing a bridge including a resistance to hold relay 300 operated. The removal of battery from the trunk leading back to the cord, releases the supervisory relay 126 which extinguishes the lamp 125 indicating to the operator that. the called party has responded. If she has not already done so, the toll operator now inserts plug 133 in jack 134 of the toll line 128 leading to the distant office and by depressing key 135 applies alternating current to the toll line to operate a signal before the toll operator. )Vhen the toll operator responds and connects the trunk 128 with the desired line (not shown), conversation may proceed.

The toll operator at the position to which the cord shown in Fig. 1 belongs can communicate with the called subscriber or with the distant toll operator by actuating her listening key LK which bridges her telephone set (not shown) across the cord. Talking current is fed to the distant subscribers line over the windings ot' the repeating coil at the distant office (not shown).

The subscriber at substation A by actuating his receiver hook causes relay 337 to intermittently operate relay 301, which applies and removes battery and ground from the trunk, thus intermittently operating the relay 126 to flash the lamp 125. Inasmuch as relay 300 is held up either through the bridge including the resistance 396 when the receiver hook is up, or over the trunk leading back to the cord when the receiver hook is down, relay 303 is maintained energized to prevent release.

It the line A was idle when selected, no ground would be present on its sleeve multiple 421 and relay 406 would immediately operate over a circuit including the lowermost armature and alternate contact of relay 419 and normal contacts of relays 417, 416, and in attracting its armature 405, opens the circuit of relay 313 (Fig which in releasing its armature 333 operates relay 302 to reverse the direction of the current flow in the trunk leading back to the cord. This circuit includes the lowermost armature of relay 320. This reversal operates polarized relay 113 at the toll board just as in the case of a busy line to disconnect the dial and extend the trunk circuit to the calling supervisory relay 126 to operate the same. In this case, however, relay 126 is not interniittcntly shunted to flash lamp 125 since relay 323 is not operated. Therefore, lamp 125 remains steadily lighted as a ringing signal whereupon the operator actuates key BK to cause the connector to apply ringing current as described. The remaining operations are the same as those traced.

When the party at substation A restores the receiver, relay 337 releases, releasing relay 301 which replaces battery on the trunk, operating relay 126 to light the lamp 125.

hen the operator desires to break down the connection she withdraws the plug 100 from jack 200 which places relay 204 across the trunk by the release of the right armature of relay 203. It the subscribers receiver is still oil' the hook relay 301 will be operated and consequently there will be no battery on the trunk. and relay 204 will notoperate. Relay 202 thus remains operated to apply battery from the normal contact of relay 204 through its right armature to hold up relay 201. Relay 201 applies battery "from a normal contact of relay 203 to the sleeves of jacks 200 to cause this trunk to test busy. When the subscriber hangs up his receiver, battery is applied to the trunk as described, which causes relay 204 to operate to open the locking circuit of relay 202, whereupon relay 202 releases. releasing relay 201, and since the relay 301 is at this time inert due to the subscriber having re placed his receiver, relay 300 is released, releasing relay 303. Relay 303 at its inner right armature removes ground from the sleeve wire 307 to deenergize switching relay 208. This relay at its uppermost armature closes the circuit of release magnet 216 to restore the incoming selector. The retraction of the left armatures of relays 300 and 303 operates the release magnets 304 and 312 of the transmission selector. The release of the outer rightarmature of relay 303 releases relays 106 and 419. Relay e08 released when relay 2320 released due to the release of relay 308. Release of the relays 406, 400 and 408 completes the circuit for the release magnet 4:10 of the connector from free pole of battery, magnet 410, oft-normal switch 413, lowermost armature and normal contact of relay 408, left armature and back contact of relay 400, lowermost armature and normal contact of relay 406 to ground.

If the plug is inserted in the jack 220 01 a trunk terminating in a manual switch, as, for example, a jack 221 at a manual board, the ring of the jack 220 being connected to battery through the right winding of impedance coil 222, relay 101 will not operate, and cut off relays 110, 111, 112 as when plug 100 was inserted in jack 200, which has ground connected to its ring. Relays 110 and 112 will operate in a circuit including the lower armature and normal contact of relay 101 to ground through sleeve relay 223. Relay 111 is marginal and does not operate in this circuit as described. Relay 110 operates relay 102 to extend the tip and ring of the plug to the relay 126. Relay 223 closes the circuit of calling lamp 224 which lights to inform the operator at the manual board of the arrival of a call from the toll board. The insertion of plug 225 operates relay 230 which disconnects battery and ground from impedance coil 222 to remove it from the talking circuit and release relay 126 to extinguish lamp 125 to indicate to the toll operator that the call has been answered and operates relay 226 to extinguish lamp 224. When the plug 225 is removed from jack 221 relay 230 releases, operating relay 126 to light lamp 125 as a disconnect signal. If the toll operator removes plug 100 from jack 220 before the plug 225 is removed. relay 223 releases and short circuits the left winding of relay 230 causing the operation of the answering supervisory relay (not shown) in the cord circuit, which lights the answering supervisory lamp as a disconnect signal.

The left-hand portion of the toll cord shown in Fig. 1 is the same as that shown and described in detail in my application, Serial No. 412,795 filed September 25, 1920 and therefore will not be described herein, since it forms no part of this invention. The leads designated M. T. are monitoring leads and extend to the operators telephone set (not shown).

What is claimed is:

1. In a telephone system, an operators position. a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a connecting circuit adapted to be connected to said trunk and baring its answering and calling ends normally disconnected from each other, means for connecting said dial to the calling end of said connecting circuit, a stepping circuit for said switches adapted to be controlled by said dial, means automatically actuated at a certain stage in building up a connection for reducing the strength of the current in said stepping circuit, and means actuated thereby for completing the continuity of the connecting cir cuit, and extending the same to said trunk.

2. In a telephone system, an operators position, a dial thercat. a trunk extending from said position and terminating in an automatic switch, other automatic switches including a toll transmission selector, telephone lines terminating in said switches, a connecting circuit adapted to be connected to said trunk and having its answerin and calling ends normally disconnected rom each other, means for connecting said dial to the calling end of said connecting circuit, a stepping circuit for said switches adapted, to be controlled by said dial, means automatically actuated at a certain stage of the connection for causing said toll trans mission selector to reduce the strength oi the current in said stepping circuit and re verse the direction of the current flow therein, and means auton'iatically actuated thereby for completing the continuity of said connecting circuit and extending the same to said trunk.

3. In atelephone system, an operatofs position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit having an electroresponsive device connected there to, means for connecting said connecting circuit to the trunk, means for connecting said dial to the calling terminal of said connect ing circuit, means automatically actuated when said connector is set on the called line for reducing the strength of the current in said trunk and, for connecting the said terminal to the said electroresponsive device. a circuit including said trunk and said electroresponsive device closed thereby, and a signal. operated by said device.

4:. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit having a bridged low resistance coil, means for connecting the calling end of said connecting circuit to the trunk and for main taining said coil disconnected therefrom, means for connecting said dial to the calling terminal of said connecting circuit to set said switches, and means automatically actuated when said connector is set on the called line for reducing the strength of the current in said trunk and for connecting said coil to said terminal.

In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit having a bridge containing a .low resistance coil and a supervisory relay, means for connecting the calling end of said connecting circuit to the trunk and for maintaining said bridge disconnected theretrom, means for connecting said dial to the calling terminal of said connecting circuit to set said switches, means automatically actuated when said connector is set on the called line for reducing the strength of the current in said trunk and for connecting the said bridge to the said terminal, and a signal controlled by said bridged relay.

6. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a connecting circuit having a bridge containing a low resistance coil and a supervisory relay, means for connecting the calling end of said connecting circuit to the trunk and for maintaining said bridge disconnected therefrom, means for connecting said dial to the calling terminal of said connecting circuit to set said switches, means automatically actuated at a certain stage in the process of building up a connection for reducing the strength of the current in said trunk and for connecting the said bridge to said terminal, a signal controlled by said bridged relay, and means controlled by the idle condition of the selected line for operating said relay to operate said signal.

7. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a connecting circuit having a bridge containing a low resistance coil and a supervisory relay, means for connecting said connecting circuit to the trunk, means for connecting said dial to the calling terminal of said connecting circuit to set said switches and for maintain ing said bridge disconnected therefrom, means automatically actuated at a certain stage in the process of building up a connection for reducing the strength of the current in said trunk and for connecting the said bridge to said terminal, a signal controlled by said bridged relay, and means controlled by the busy condition of the called line for intermittently operating said relay to intermittently operate said signal.

8. In a telephone system, an operators position, a dial thereat, a trunk extending from terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a connecting circuit having a bridge containing a low resistance coil and a supervisory relay, means for connecting said connecting circuit to the trunk, means for connecting said dial to the calling terminal of said connecting circuit to set said switches and for maintaining said bridge disconnected therefrom, means automatically actuated at a certain stage in the process of building up a connection for connecting the said bridge to said terminal, a signal controlled by said bridged relay, a second signal at said position, and means controlled by the busy condition of a trunk group for operating said second signal.

9. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines termi nating therein, a connecting circuit adapted to be connected to said trunk and having its answering and calling ends normally disconnected from each other, means for connectmg said dial to the calling end of said connecting circuit to set said automatic switches, and means automatically actuated when the connector is set on the called line for automatically completing the continuity of said connecting circuit and for automatically disconnecting said dial therefrom.

10. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a connecting circuit adapted to be connected to said trunk, means for connecting said dial to said connecting circuit to set said automatic switches, means automatically actuated at a certain stage in the process of building up a connection for auton'iatically completing the continuity of said connecting circuit, a signal at said position individual to said dial, and means automatically actuated when one of said switches encounters a busy said position and trunk group for operating said signal.

ll. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a connecting circuit having its ends normally disconnected irom each other adapted to be connected to said trunk, a relay automatically operated therel'iy to connect said dial to said connecting circuit to set said automatic switches, means automatically actuated at a certain stage in the process of building up a connection for completing the continuity of said connecting circuit, a signal at said posit ion operated by the operation of said relay and the connection of said connecting circuit to said trunk, means for rendering said signal inert when said dial is moved otl normal, and means automatically actuated when one of said switches encounters a busy trunk group for operating said signal.

12. In a telephone system, a toll operators position, a dial thereat, a toll trunk extend ing from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a toll cord circuit having an GlGClITOI'QSPOIISlVG device connected thereto, answering and calling plugs for said cord circuit, said plugs being normally disconnected from each other, means for connecting said dial to the calling plug and thence to the trunk, means automatically actuated when the connector is on the called line for completing the continuity of said cord to operate said device, and a signal controlled by said device.

13. In a telephone system, a toll operators position, a dial thereat, a toll trunk ext-ending from said. position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a toll cord circuit having an electroresponsive device con nected thereto, answering and calling plugs for said cord circuit, said plugs being normally disconnected from each other, means for connecting said dial to the calling plug and thence to the trunk, means automatically actuated when the connector is set on the called line for con'ipleting the continuity of said cord to operate said device, a sig nal controlled by said device, and means for automatically operating said signal in one manner it the line is idle and in another manner it the line is busy.

14. In a telephone system, a toll open ators position, a dial thereat, a toll trunk extending from said position and terminating in an automatic switch, other automatic switches including aconnector, telephone lines terminating therein, a toll cord having an electroresponsive device connected thereto, answering and calling ends for said cord circuit, said plugs being disconnected from each other, means for connecting the said dial to the calling plug automatically upon the connection of said plug to said trunk, means automatically actuated when the connector is set on the called line for disconnecting said dial from said cord and for completing the continuity of said cord, a circuit including said trunk, said cord and said device to operate said device, a signal controlled by said device, means automatically actuated by the idle condition of the called line to control said device to perate said signal in one manner, and means automatically operated by the busy condition of the called line for controlling said device to operate said signal in another man nor.

15. In a telephone system, an operators position, a dial there-at, a trunk extending from said position and terminating in an automatic switch, other automatic switches, telephone lines terminating therein, a trunk extending from said position and terminating in a manual switcn, a connecting circuit l'iaving its calling and called terminals normally disconnected from each other, means automatically operated when said connecting circuit is connected to said trunk for connecting said dial thereto to set said automatic switches, means automatically operated at a certain stage in the process of building up a connection for completing the continuity of said connecting circuit, means automatically actuated when said connecting circuit is connected to said second named trunk for completing the con tinuity of said connecting circuit, and an electroresponsive device connected to said connecting circuit and operated thereby.

16. in a telephone system, an operators position, a dial thereat, a trunk extending "rum said position and terminating in an automatic switch, other automatic switches, telephone lines teri'ninating therein, a. trunl; extending from said position and terminating in a manual switch, a connecting circuitlia'ving its answering and calling ends norin ally disconnected from each other, a relay controlled by the sleeve resistance at said trunks and utomatically operated when said connecting circuit is connected to said first trunk for connecting said dial thereto to set said automatic switches, means automatically actuated at a certain stage in the process of lmilding up a connection for completing the continuity of said connectiu circuit, means automatically actuated when said connecting circuit is connected to said second named trunk for completing the continuity of said connecting circuit, and an elcctroresponsive device connected to the connecting circuit and operated thereby.

17. In a telephone system, an operatofis position. a dial thereat, a trunk extending trom said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terurinating therein, a connecting circuit having an electroresponsi've device connected thereto, means for connecting said connecting circuit to the trunk, means for connecting said dial to the calling terminal of said connectingcircuit, a relay adapted to disconnect said dial, a circuit including said dial, said relay and said trunk, said relay being constructed and arranged not to operate in said circuit, means automatically actua ted when said connector is set on the called line tor effecting a circuit change in said trunk to operate said relay to disconnect said dial from the connecting circuit and connect said electroresponsive device to the trunk to operate said device, and a signal controlled by said device.

18. In a telephone system, an operators position, a dial and a polarized relay common to said position, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit having an electroresponsive device connected thereto, means for connecting said connecting circuit to the trunk, means for connecting said dial to the calling terminal of said connecting circuit and thence to the trunk, means automatically actuated when said connector is set on the called line for reversing the current in said trunk to operate said polarized relay to disconnect said dial from the connecting circuit and for connecting said electroresponsive device to the trunk to operate said device, and a signal controlled by said device and operated in one manner it' the called line is idle and in another manner if it is busy.

19. In a telephone system, an operator position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit having an electroresponsive device connected thereto, means for connecting said connect ing circuit to the trunk, means for connecting said dial to the calling terminal of said connecting circuit and thence to the trunk, means automatically actuated when said connector is set on the called line for reversing the current flow in said trunk and reducing its strength, a polarized relay common to said position operated by said current reversal to disconnect said dial from the connecting circuit and for connecting said electroresponsive device to the trunk to operate said device, and a signal controlled by said device.

20. In a telephone system, an operators position, a dial thereat, a trunk circuit extending from said position and terminating in an automatic switch and including said dial and the impulse relay of said switch, telephone lines terminating therein, an operators cord circuit adapted to be connected to said trunk and having its answering and calling ends normally disconnected from each other, and means automatically actuated when said automatic switch is set on the called line for completing the continuity of said cord circuit.

21. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, an operators cord circuit adapted to be connected to said trunk and having its answering and calling ends normally disconnected from each other, means automatically actuated when the calling end of said cord circuit is connected to said trunk for connecting said dial to the calling end of said cord circuit to set said automatic switches, and means automatically actuated when said connector is set on the called line for auton'iatically completing the continuity oi said cord circuit.

22. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit, means for manually connecting the same to said trunk, means for connecting said dial to said connecting circuit, and means automatically actuated when the connector is set on the called line for disconnecting said dial from said connecting circuit.

23. In a telephone system, anoperators position, a dial thereat, a trunk terminating at said position in a manual switch and at its other end in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a connecting circuit having a manual terminal for connection with said trunk, a relay in said connecting circuit operated by the connection of said connecting circuit to said trunk for connecting said dial. to said connecting circuit, and means automatically actuated when said connector is set on the called line for disconnecting said dial from said connecting circuit.

24. In a telephone system, an operators position, a dial thereat, a toll trunk terminating at said position in a and at its other end in an automatic switch, other automatic switches including a connector, telephone lines terminating therein, a toll cord having a plug for connection with said trunk, a relay individual to said cord circuit operated by the connection of said cord to said trunk for connecting said dial to said cord, and means automatically actuated, when the connector is set on the calling line for disconnecting said dial from said cord.

I 25. In a telephone system, a toll operators position, a dial thereat, a trunk terminating at said position in a jack and at its other end in an automatic switch, other automatic switches including a toll connector and a toll transmission selector, telephone lines terminating in said connector, a toll cord circuit, answering and calling plugs therefor, a relay individual to said cord circuit operated by the connection of the calling plug to said jack for connecting said dial to said cord, and means automatically actuated when the connector is set on the cal ed line for causing said toll transmit-lesion se leetor to dcencrgize said relay to said dial from said cord circuit.

26. In a telephone system, a toll operators position, a dial t-hereat, a trunk terminating at said position in a jack and at its other end in an automatic switch, other automatic switches including a toll connector, telephone lines terminating thereat, a toll cord circuit, answering and calling plugs therefor, a relay operated by the connection of the calling plug to sail acla: for connect-ing said dial to said cord, a supervisory relay in said cord circuit, a lamp controlled thereby, means autoi'i'iatieally actuated when the connector is set on the called line for disconnecting said dial from said cord and extending said cord to said trijinlr, means controlled lay the idl condition of the called line for operating said supervisory relay to light said lamp, and means controlled by the busy condition of the called line for operating said relay to tlash said lamp.

27. In a telephone system, an operators position, a dial thereat, a trunk extending from said position and terminating in an automatic switch, a connecting circuit adapted to he conne :ted to said trunk, electromagnetic means operated by the connection of said connecting circuit to said trunk for connecting said dial to said connecting circuit, and a signal at said position operated in re ponse to the actuation of said electromagnotic means.

28. In a telephone system), an operatofis position, a dial thcreat, a trunk extending from said position and terminating in an automatic switch, a connecting circuit adapted to he connected to said trunk, elec tromagnetic means operated by the connection of said connectingcircuit to said trunk for connecting said dial to said connecting circuit, a signal at said position operated in response to the actuation of said electromagnetic means, and means for rendering said signal inert when said dial is moved off normal.

29. In a telephone system, an operators position, a cial thereat, a trunk extending from said position and terminating in an automatic switch, a cord circuit adapted to be connected to said trunk, a relay operated by the connection of said cord circuit to said trunk for connecting said dial to said cord, and a signal actuated by the operation of said relay.

30. In a telephone system, an opera position, a dial thercat, a trunk enter from, said position and terminating i1: automatic switch, a cord circuit adan 7 be connected to said trunk, a relay 0' by the connection of said cord circuit t trunk iiorconnectingsaid dial to said c signal actuated by the operation of said relay,

and means for rendering said signal inert when said dial is moved oil normal.

31. In a telephone systen'i, an op uiw. position, a dial thereat, a i from said position and u iinating ii an automatic switch, groups of trunks termh nating therein, a cord circuit for coni'ic-"tiou with said trunk, a first relay at said tion, a loop circuit including contacs sail dial and relay and including the ii pulse relay or said automatic switcl ciir-y upon the connection of said cord trunk, a second relay operated wli, loop circuit is closed and having ada-*.ed to shunt the cont; is of relay, a :ir-uit for operating first .1 closed when said dial is moved olt normal a circuit including a signaling device and normal contacts oi? said second relay, and means actuated when said switch encounters 35 a busy trunk group releasing socory'. relay to close said circuit to operate sai' signaling device.

39,. In a telephone system, an operatofis position, a dial thercat, a trunk extending from .2 d position and terminating in an autmuatic switch, groups of trunks te inatii'ig therein, a cord circuit for connec u with said trunk, a first relay at said position,

a loop circuit including contacts of said dial and relay and including the impuse relay of said automatic switch closed upon the connection of said cord to said trunk,

a second relay operated when, said loop circi is closed and havir contacts adapted 190 to shunt the contacts of said first relay, a circuit for operating said first relay closed when said dial is moved otlt' normal, a circuit including a. lamp, an interrupter, and normal COE'fitCtS of said second relay, and means actuated when said switch encounters a busy trunk group for releasing second relay to close said lain o circuit to flash said lamp. A

In witness whereof, I hereunto suhserihc my name this 2nd day of November, it. i). 1921. I 

